What type of metabolism can only proceed in the presence of oxygen?

Aerobic metabolism refers to the biochemical processes that require oxygen to generate energy. This type of metabolism occurs in almost all higher forms of life as it efficiently produces adenosine triphosphate (ATP)—the energy currency of the cell—by breaking down glucose or other substrates in the presence of oxygen. During aerobic metabolism, oxygen acts as the final electron acceptor in the electron transport chain, allowing for the complete oxidation of substrates, which maximizes ATP production.

In contrast, anaerobic metabolism, cellular respiration, and fermentation can occur in the absence of oxygen or with less dependency on it. Anaerobic metabolism does not use oxygen and generates energy through alternate pathways, yielding less ATP. Cellular respiration is a broader term that encompasses both aerobic and anaerobic processes but does not solely denote the presence of oxygen. Fermentation also operates without oxygen and is less efficient than aerobic metabolism, producing only a limited amount of ATP. Therefore, the defining characteristic of aerobic metabolism is its exclusive reliance on oxygen for energy production.